Multioffice telephone system



May 2, 1933. NELSON 1,907,087

MULTIOFFICE TELEPHONE SYSTEM Filed July 6, 1922 'YSheets-Sheet 1 TIUETZ DI- HEJTETL L-N5l5uu May 2, 1933.

M. L. NELSON MULTIOFFICE TELEPHONE SYSTEM Filed July 6, 1922 7 Sheets-Sheet 3 \Q E. YA L w xm K May 2, 1933. M. L. NELSON NULTIOFFICE TELEPHONE SYSTEM 7 Filed July 6, 1922 7 Sheets-Sheet 4 May 2, 1933.

M. L. NELSON 1,907,087 HULTIOFFICE TELEPHONE SYSTEM Filed July 6, 1922 7 Sheets-Sheet 5 m- H'EJTL LNEZ'aun' Eff g:

Filed July 6, 1922 7 Sheets-Sheet 6 y 2, 1933. M. L. NELSON 1,907,087

MULTIOFFICE TELEPHONE SYSTEM Filed July 6, 1922 7 Sheets-Sheet 7 Two Step Relays m- HTfhT-L LNsZscm Patented May 2, 1933 UNITED STATES PATENT OFFICE MARTIN L. NELSON, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

ASSOCIATE!) ELECTRIC LABORATORIES, INC., OF CHICAGO, ILLINOIS, A. CORPORA- TION OF DELAWARE MULTIOFFICE TELEPHONE SYSTEM Application filed July 6, 1922. 'Serial No. 573,175.

The present invention relates in general to multiofiice telephone systems, but more in particular to systems of this character ofiices of the type mentioned irrespective of the number of digits in the telephone numbers. While various kinds of numbers may in which registering mechanism is employed for registering telephone numbers as they are called, in combination with translating and sending mechanism for routing the calls to their destinations, and the main object is to produce a new and improved director, which may be considered as an improvement on the director shown and described in the British Patent 194,580. Although, as stated, the invention is applicable generally to multi-ofiice systems of the tye mentioned, as to a large number of features it is especially adapted for use me multi-ofiice system comprising both automatic and manual oflices.

It is common practice, when converting a multi-oflice manual system to automatic operation, to replace the manual equip ment by automatic equipment one ofiice at a time, the transition period often extending over a period of several years. Accordingly, during the time when some of the ofiices are being operated automatically and others manually, arrangements must be made whereby the entire system may op. erate as a unit. The director shown inthe present application is designed for use in an automatic ofiice of a mixed ofiice multiofiice system comprising two or more automatic oflices, 'an individual line manual ofiice, and aparty line manual oflice. Calls are trunked from one automatic ofiice to another according to standard automatic practice, while calls from an automatic ofiice to the manual oflices are preferably handled by call indicating apparatus adapted to display the called numbers to operators according to the general principles set forth in U. S. Patent 1.475.590, granted Nov. 27 1923, to Martin and Willis.

In a complex system of the foregoing character it will generally happen that the telephone numbers are not uniform throughout all the oflices as to the number of digits, and a special object of the invention. therefore, is the provision of a director which is 0 adapted to set up connections to various be taken care of, a system will be assumed by way of example, in which the numbering scheme for each of the automatic oflices is laid out according to the jack per station plan, according to which plan the subscribers number comprises only four digits, whether the subscriber is a party line sub scriber or an individual line subscriber; in

which the party line manual ofiice numbering scheme is such that each subscribers number comprises four digits for determining the called line and a fifth digit for determining the desired subscriber on the called line; and in which the individual line manual oflices are equipped with the same kind of call indicators at the incoming call indicator B positions as are used in the party line manual offices, which call indicators require five digits to be called in the subscribers number before the number isdisplayed to the operator. In the individual line manual offices, the fifth digit lamps are removed from the call indicators and the fifth digit dialled has no function other than to switch the indicator into position to display the four digits of the subscribers number to the operator. The above arrangement allows the standard five digit call indicators to be in each oflice of the system, which from a manufacturing standpoint alone, is a considerable advantage.

In the director, suitable circuit arrangements are made such that, when the call is going to an automatic ofiice, the four digits of the subscribers number are dialled and the director is cut off; when a call is going to a party line manual oflice, the five di 'ts vide means whereby the director is automatically cut off and the connection switched through to the first selector, if no dialling occurs during a predetermined interval, this being done under the assumption that, since no digits are dialled, the subscribers line is accidentally short circuited or grounded and, consequently, that the seizure of the director was not due to the subscriber initiating a call; and whereby if no dialling occurs during a predetermined interval after the subscriber has dialled one or more digits, the call is trunked through automatically by the director to the monitoring operator.

A further object is the production of circuit arrangements, whereby the ofiice register of the director is automatically rotated one step upon the calling of the digit 0, which is the digit dialled when the long distance operator is desired, so as to place the director in connection to send out the code necessary to trunk the call to the long distance operator.

Another object is the provision of circuit arrangements, whereby a paystation subscriber may call the long distance operator without depositing a coin, but cannot obtain connection with a subscribers line without first depositing a coin, the circuit arrangements being such that the call is trunked through immediately to the monitorin operator, in case the first digit dialled y a paystation subscriber is other than 0, unless he has deposited a coin.

A still further feature is the provision of circuit arrangements, whereby the same director may be used by subscribers on paystation lines and by subscribers on other lines, and whereby the director is rendered fully operative automatically independent of any act performed by a subscriber when he is calling from any line other than a pay.- station line.

The other features relate principally to circuit improvements and will become apparent upon a further perusal of the specification.

Referring to the drawings, Fig. 1 shows a paystation line extending from the paystation telephone A to the individual line switch C in the exchange; Fig. 2 shows a paystation repeater R accessible to the line of substation A, and a secondary switch SS which has access to a plurality of directors; Fig. 3 shows an ordinary station A, line, individual line switch C, a repeater R accessible to the subscribers line switch C, the secondary switch SS, individual to the repeater R, and having access to the same directors as the secondary switch SS, Fig. 2, and a first selector D associated with the repeater R; Figs. 4-7, inclusive, show the improved director; and Fig. 8 is a layout showing together.

how Figs. 1 to 7, inclusive, join The automatic substation A, Fig. 1, has the usual talking, signalling, and switch control instrumentalities, and being a paystation telephone, has COIII controlling and coin controlled mechanism. The substation A, Fig. 3, is similar to the substation A, except that the circuit is somewhat simpler and no coin mechanism is provided.

The line switch C, Fig. 1, in which the line of substation A terminates is of the wellknown rotary type in which the wipers have no normal position and move in a forward direction only. The line switch C, Fig. 3, is identical with the line switch C.

The repeater R, Fi 3, which is inserted in the trunk ahead 0 the first selector D, is provided for the purpose of repeating the number dialled by the calling subscriber into the director and for repeating from the director into the automatic switches. The repeater R, Fig. 2, is similar to the repeater R with the exception that the repeater B, being a paystation repeater, has arrangements for deferring the grounding of a certain conductor in the director trunk until the calling subscriber has deposited a suitable coin. The repeater R has also the usual arrangements for collecting or refunding the coin when the calling subscriber hangs up.

The secondary switch SS, Fig. 2, is mechanically identical with the line switch C or the line switch C, and has its circuits suitably arranged for selecting an idle director when the trunk with WlllCll it is associated is seized. The secondary switch SS is mechanically identical with the secondary switch SS and haspractically the same circuit. Such differences as exist will become apparent when the hereinafter given detailed description is read.

The secondary switches SS and SS, together with the other secondary switches in the same secondary group, have access to a plurality of directors such as the one shown in Figs. 4-7, inclusive, by way of four conductor trunks such as the one comprising conductors 101-104, inclusive. The director accessible by way of this latter trunk comprises, in addition to various controlling relays, the master' digit controller MDC, Fig. 4; the ofiice register OR, and the intermediate distributing frame IDF, Fig. 5; a sequence switch S, Fig. 6; the digit registers DR-DR, inclusive, Fig. 7; and the sender which comprises certain relays shown in Fig. 6 and the counting relays shown in the lower part ofFig. 7

The master digit controller MDC Fig. 4, is mechanically a so-called minor switch and has a pair of wipers 253 and 254 which are moved in a forward direction by stepping magnet 251, and which are released to normal by release magnet 250. Ofi normal contacts 228 are provided for the purpose of 1 opening the circuit of release magnet 250 when the wipers reach normal position. The digit registers DR-DR*, inclusive, are each mechanically identical with the master digit controller MDC, with the exception that the wipers of the digit registers are normally out of engagement with their associated bank contacts, whereas the wipers of the master digit controller are normally in engagement with the first associated bank contacts. A further difference is that each'of the digit registers is provided with only one wiper and each has an extra pair of ofi normal contacts, as shown.

The office register OR, Fig. 5, is a Strowger switch of the vertical and rotary type, having 100 sets of contacts arranged in ten horizontal rows or levels. This switch is directively controlled in its vertical and rotary movements by impulses delivered to its vertical and rotary magnets by way of the master digit controller MDC. This oiiice register is provided with four wipers 260- 263, inclusive, which have access to each of the 100 sets of bank contacts, of which four sets are shown. The vertical, rotary, and release magnets of the switch are indicated by the reference characters 229-231, inclusive, respectively. This switch is provided with an off normal combination comprising s ring 232 and its upper contact and also t e normally open contacts controlled by spring 232. The normally open contacts controlled by spring 232 are adjusted to close when the switch wipers are raised opposite the first level of bank'contacts. Spring 232, however, does not break away from its associated lower contact and come into engagement with its upper contact until the wipers of the switch are raised opposite the second levelof bank contacts. This adjustment enables circuit arrangements to be made, whereby the switch is released each time it comes to rest opposite the first level of bank contacts, which level of contacts is left dead and does not correspond to any oflice numbers. The switch OR is provided also with the tenth level spring combination comprising springs 233-235, inclusive, which are operated by the switch shaft when the latter is raised opposite the tenth level of bank contacts. The bank levels 2-9, inclusive, of the ofiice register OR are wired to setsof terminals on the left hand side of the frame IDF. The first level, as before stated, does not correspond to any office numbers and, consequently, is not wired up to the IDF. Of the tenth level of bank contacts, only the first set is wired to the IDF. the nine remaining sets not being used in this particular case.

The ten impulse conductors comprisingconductors 291-300, inclusive, together with the special conductors 301-306, inclusive, are terminated on the right hand side of the IDF, and each may be multiplied to as many contacts as desired in order to facilitate the running of any desired number of jumpers to each conductor, only one contact for each conductor being shown. The ten impulse conductors represent the digit impulses, the last figure in the reference character applied to each conductor indicating the number of impulses the conductor represents.

Of the special conductors 301-303, inclusive, conductor 301 is the switch conductor and is used to switch the director through when the number called is not a subscribers number, such as, for example, when the lon distance operator is being called by the director, by dialling 46.

Conductor 302 is the automatic ofiice discriminating conductor and, accordingly, a jumper is run to it from the fourth bank contact of each set of contacts that represents an automatic office, so as to place the director in condition to send properly and switch through at the right time, the director being set so as to add the digit 1 to the individual line manual numbers so as to switch the call indicators in the individual line manual oflices after the four digits of the number are dialled.

The fourth contact in each set of contacts that represent a manual party line number is jumpered to conductor 303, so as to place the director in condition to receive and send out the digit correspondin to the desired station on the calledparty ine.

Conductors 304-306, inclusive, are the usual skip conductors and are provided for the purpose of causing the sequence switch S, Fig. 6, to advance automatically past the second, third, and fourth positions, respectively, when these conductors.

The sequence switch S, Fig. 5, is a step by step rotary switch ofthe type in whic the wipers move in a forward direction only, and in which the wipers are advanced when the stepping magnet retracts its armature rather than when the stepping magnet attracts its armature.

In the drawings the slow acting relays are denoted by shading the lower portion of their cores, or by making the upper portion of their cores solid black, depending upon whether the relay is merely slow to release or is also slow to operate. The shaded portion on the lower end of the core of arelay indicates that that relay is slow to release after its circuit is opened, but is not appreciably slow to operate u on a closure of its circuit. On the other and, a solid black portion on the upper end of the core of a relay indicates that that relay is slightly slow to pull up after its circuit is closed, in addition to being slow to release after its circuit is opened.

The general object and scope of the injumpers are properly run to When the receiver is removed at substation A, a circuit is closed over the associated line conductors for relay 111 of the line switch C. Relay 111, upon energizing, closes a circuit for switching relay 110 and ste ping magnet 112 in series at armature 11 and at armature 116 connects test wiper 119 to the junction of relay 110 and magnet 112. In case the trunk upon whlch the wi rs of the line switch C are stand ing is ldle, the latter operation has no efiect and switching relay 110 energizes immediately. However, assuming the trunk upon which the wipers are standing to be busy, switching relay 110, being short circuited bythe ground potential which is present on the test contact thereof, does not energize, and the switch wi ers .118-120, inclusive, are automatically 8. vanced step by step 1n search of an idle trunk by the buzzerlike action of steppin magnet 112. When an idle trunk is reac ed, which trunk it w1ll be assumed is the one comprising conductors 121-123, inclusive, switching relay 110, being no longer short circuited, energizes in series with stepping magnet 112, stepping magnet 112 not energizing at this time on account of the high resistance of switchin relay 110. Upon energizing, switching refay 110 opens the test circuit and prepares the holding circuit at armature 114, thereby making the seized trunk busy immediately, andat armatures 113 and 115 disconnects the conductors of the calling line from the winding of line relay 111 and ground and extends them by way of wipers 118 and 120, trunk conductors 121 and 123, and the resting contacts of armatures 131 and 134 and sa d armatures to the windin of line relay 125 of the repeater R, Line relay 125, upon energizing, closes a circuit for line relay 137 of the secondary switch SS at armature 128. Relay 137, upon energizing, disconnects release trunk conductor 122 of the repeater R from release trunk conductor 161 of the selector D, and places ground on the former at armature 141,- thereby establishing the usual holding circuit for the line switch C before line relay 111 has had time to deenergize; closes a circuit for switching relay 138 and stepping magnet 147 in series at armature 140; and at armature 139 connects test wiper 149 to the junction of switching relay 138 and step-' ping magnet 147. In case the trunk upon which the wipers of the switch are standing is idle, the last mentioned operation does not have any effect, and switching relay 138 energizes in series with stepping magnet 147. However, assuming the trunk upon which the wipers are standin to be busy, switching relay 138 is short clrcuited by the ground potential which is present on the test contact thereof, and the wipers 148 151, inclusive, are advanced step by step in search of an idle trunk by the buzzerlike action of stepping magnet 147. When an idle trunk is reached, which trunk it will be assumed is the one comprising conductors 101-104, inclusive, test wiper 149 encounters an ungrounded test contact and switching relay 138, being no longer short circuited, energizes in series with stepping magnet 147. Stepping magnet 147, however, does not energize at this time on account of the high resistance of switching relay 138. Upon energizing, switching relay 138 opens the test circuit and places ground on test wiper 149 at armature 144,,and at armatures 143, 145, and 146 connects up wipers 148, 150, and 151, respectively. In response to the placing of ground on test wiper 149, conductor 1.02 is grounded, whereupon relay 204, Fig. 4, energizes; connects the timed impulse lead 209 to the lower winding of relay 201 at armature 217 disconnects ground from the release lead 242 at armature 216; and at armature 215 prepares a locking circuit for relay 201. As a result of the connecting up of wiper 151 of the secondary switc SS, ground is placed on leadv 104, thereby grounding the last eight contacts in the lower bank of the master digit control switch MDC, Fig. 4, and closing a circuit for relay 208. Relay 208, upon energizing, disconnects relay 206from conductor 237 at armature 227, As a result of the connecting u of wiper 150 of the secondary switch SS relay 127 of the re eater R is connected up to the outgoing irector impulse conductor, whereupon repeating relay 127 energizes over the following circuit from ground by way ofarmatures 414 and 417 of relays 381 and 382, Fig.6, and their resting contacts, conductor 248, resting contact of armature 220 of relay 206, Fig. 4, and

said armature, conductor 103, wiper 150,

armature 145 and its working contact, and

re ating. relay 127 to battery. Repeating re ay 12 upon energizing, closes a bridge across conductors 160 and 162 of the selector D at armature 136, whereupon line relay 163 of the selector D energizes and closes a circuit for release relay 164 at armature 174. Release relay 164, upon energizing, opens a point in the circuit of release magnet 167 and prepares a circuit for vertical magnet 168 at armature 176, and at armature 175 places ground on release trunk conductor 161. 11 response to the connecting ui o'f wiper 148 of the sec-v ondary switch S a connection is extended from armature 129 of line relay 125, by way of armature 143 and its working contact, wiper 148,. conductor 101, armature 390 and its resting contact, series relay 202,

wi r 253 of the master digit control switch C, conductor 249, vertical magnet 229 of theoflice register OR, and the right hand winding of the trunk tone machine TT to batter Since armature 129 of line relay 125 of the repeater. R is now attracted, and since that armature is connected with the lower heavy talking conductor through condenser 124, the calling subscriber hears the tone Bproduced b the trunk tone machine TT, ig. 5, and nows that he may proceed with the call. 1

Before the establishing of the desired connection is proceeded Wlth, theffunction of certain equipment shown in Fi 4 will be taken upmore in detail. For is purpose, it will be assumed that, the subscriber at substation A is called away from his telephone after the receiveris removed, and that e does not replace the receiver on the'hook.

Now, when ground is placed on the common timed conductor 209, Fig. 4, by the associated cam springs, which occurs about every half minute or so, a circuitis closed for the lower winding of the marginally ad'usted rela 201, whlch winding is comp of a smal number of turns of wire having a high specific resistance. Consequently, re-

lay 201 energizes sufliciently to operate the,

lightly adjusted armature 209, but not sufficiently to operate the more stiflly adjusted armature 210. Armature 209, u on being operated, grounds the upper win g of relay 201 byway of armature 215 and its working contact, and the resting contactof armature 212 and said armature. No current flows through the upper winding at this time, however, owing to the fact that grounded at both terminals. When it is groun is removed from the common conuctor 209, current flows through the upper and lower windings of relay 210 in series,

whereupon the said relay energizes fully, and at armature 210 disconnects the timed imgulse lead from its own lower winding, an

extends it to relay 376 by way of armature 218 and its resting contact, and thenormally closed contacts controlled by armature 389. When the-next ground rm ulse is placed on conductor 209, a circuit is clbsed for relay 376. Relay 376, upon energizing, locks itself to conductor 102 at armature 389, and at armature 390 disconnects conductor 101 from relay 202 and connects it to ground instead. When this occurs, switching relay 126 in the repeater R, with which conductor 101 is connected, energizes and extends the connection through to the selector D and releases the director ina manner to be described fullyhereinafter. This is done so as to not tie up the director for an undue length of time. The selectors, such as D, are provided ordinarily with timed supervisory means (not shown) which brings in a signal in case a selector is held lon er than a predeterminedinterval without being operated.

It will be assumed now that the subscriber at substation A is not called away from his telephone, and that he 0 rates his calling devlce in accordance wi the first ofiice digit 9 of the desired number before ground is placed on the common lead 209 the second time, i.- e., before relay 376, Fig. 4, is energized. That bein the case, line relay 125 of the repeater R to each Interruption of its circuit at the calling substation, and, upon each deenergization, places'ground on conductor 101 at armature 129. Each time und is placed on conductor 101, an impu delivered to vertical magnet 229 by wa of a previously traced circuit which includes series relay 202, Fig. 4, and wi or 253 of the master digit cont-r01 switch 0. B the operation of vertical magnet 229, which receives nine impulses of current at this time, the wipers 260-263, inclusive, of the ofiice register OR are raised ste by step until they stand'osppos'ite the ninth level of bank contacts. low acting series relay 202 is energized during the entire vertical move-' ment of the wipers and, upon energizing, disconnects ground from'conductor 241 at armature 212, thereby opening the locking circuit of relay 201 and allowing it to deenergize in case it is energized, and at armature 212 and its working contact closes a circuit for relay 203. Relay 203, u on energizing, prepares a circuit for re ay' 205 and for stepping magnet 251 of the master digit control switch at armature 214.

.Art the end of-the vertical movement of the switch OB, series relay 202 deenergizes and opens the circuit of ture 212. Relay 203, being slow acting, retains its armature attracted for an interval. As a further result of the deenergization of relay 202, it completes the circuit of stepping magnet 251 of the switch MDC at armature 212. Stepping magnet 251,

deenergizes in responsese of current is relay 203 at arma- I upon energizing, advances the wipers 253 and 254 into engagement with the second set of bank contacts. Relay 205 energizes in multiple with ste ping magnet 251; closes a locking circuit or itself and opens its'initial circuit at armature 219; and at armature 218 disconnects the timed im ulse lead.

connects it to rela 206, thereby preparing the direcextension fromconductor 243 an tor to' cal the monitoring operator in case the subscriber waits too long between the dialling of the digits of the number. After an interval, slow acting relay 203 deenergizes and opens the circuitof stepping mag net 230 of the switch MDC. The director is now in readiness to register the second ofiice digit.

In order to explain how the call is trunked through to the monitoring operator in case the calling subscriber delays too long be.'

tween the dialling of the various digits, it will be assumed that the subscriber does not dial the second digit in the office number within the prescribed time limit. That being the case, relay 201 is energized and is locked u in the hereinbefore described manner t e first time ground is placed onthe common timed lead 209 after the dialling of the first digit. The next time ground is placed on the common timed conductor disconnects ground from locking conductor 244 at armature 223, so as to allow relay 377, Fig. 6, to deenergize in theevent that it is energized; and at armature 224 closes a circuit for relays 207 and 256 in series. In response to the ground potential being placed on release conductor 242, release magnet 231 of the oflice register OR energizes in series with the normally open contacts controlled by ofi normal spring 232, whereupon the shaft and wipers of. the switch OR are restored to normal position in the usual manner, the circuit of release magnet 231 being.

opened by the switch shaft when the latter reaches normal position. Likewise, release magnet 250 of the master digit control switch MDC energizes through ofinormal contacts 228 and restores the wipers 253 and 254 to normal. Relay 207, upon energizing, locks itself to the grounded conductor 102 at armature 225, and at armature 226 connects the resting contact of armature 224 to start conductor 247. Relay 256, Fig. 5, upon energizing in series with relay 207, connects up the four wi 267, inclusive, of the 0 ca register OR-to the group of special conductors 284-287, inclusive, respectively. The opening of the circuit of repeating relay .127 of the repeater R is forthe purpose of allowing any partly established connection that might be set up to release. Since the connection extends only to the selector D, the line and-release relays thereof are deenergized one.

after the other, whereupon the switch shaft steps ug one step and is then restored to normal y the release magnet. When ground r conductors 264.

is removed from the common conductor 209 after an interval of; a second or so, relay 206.] deenergizes-and places ground on start conductor'247at armature 224 by way ofarmature 226 and its working contact, and at armature 220 again closes the circuit of repeating relay 127 in the repeater R, whereupon the line and release relays of the selector D energize again. In response to ground being placed upon start conductor 248, the sending portion of the director is set in 'motion, and; the number 311 corresponding to the terminals on the right hand side of the IDF to which the special conductors 284-286, inclusive, are jumpered, is sent out in a manner to be described fully hereinafter. i 7 Z Assuming now that the calling subscriber does not wait too long between the calling of the various digits, and consequentl that he calls the second digit 1 in the esired office number before ground is placed on the common conductor 209the second time after the diallingof the first digit in the number, one interruption is thereby produced in the circuit of line relay 125 of the repeater R. Upon deenergizin'g in response to this interruption, line relay 125' sends an impulse of current over conductor 101. This impulse of current extends byway'of a path previously'traced to wiper 253 of the master digit control switch MDC, and thence by way of the second associated bank contact,

conductor 246, and the contact of the tenth level spring 233 andsaid spring to rotary magnet 230 of the oiliceregister OR. Rotary magnet 230, upon energizing, advances the wipers 260-263, inclusive, into engagement with the first set of bank contacfs in the ninth level. By the combinedaction of slow acting series relay 202 and slow acting relay 203, an impulse of current is delivered, as before,'to stepping magnet 251 of the master digit control switch at the end of the calling of the second digit, whereuponthe wipers 253 and 254 are advanced into-engagement with the third set of bank contacts. Wiper 253, u on comin into engagement with its 'third associatec l bank .contact, prepares a circuit for ste ping magnet 445 of the di it register DE,

III

which register is the one t at responds to the calling of the first digit in the subscribers number, and wiper 254, upon coming into engagement with its associated con- .tact,'places ground on start conductor 247 by way of the grounded conductor 104, therettg starting the director to sending out theo ce code, as will be explained subsequently.

pulses of current are delivered to stepping" magnet 445 of the digit register DR by way of a circuit previously traced to wi er 253 of the master digit control switc and thence by way of the third associated bank contact and series relay 444. As a result, wiper 451 of the switch DR is advanced step by step until it comes into engagement with the fifth associated bank contact. Slow actin series relay 444 is maintained energized uring the stepping movement of the switch and maintains con uctor 357 disconnected at armature 449. At the end of the stepping movement, relay 444 deenergizes and places ground on conductor 357 at armature 449 so as to allow the first digit in the subscribers number to be sentout. This round potential comes through ofi normfi contacts 447 which became closed when the switch wiper moved from its normal position. At the end of the series of lmpulses, the wi ers of the master digit control switch MD8 are advanced another step in I the hereinbefore described manner, whereupon wiper 253 comes into engagement with the conductor leading to the ste ping magnet of the digit register DR.

he subscriber now calls the three remaining digits 6, 7, and 8 in the desired number, whereupon the digit register switches DIV-DR, inclusive, are operated to step their wipers around in accordance with the three remaining digits, res ectively, the operation of each of t ese switches being the same as that of the digit re ister DR, previously described.

11 response to the placing of ground upon start conductor 247 at the end of the calling of the second ofiice digit, as explained hereinbefore, relay 375, Fig. 6, energizes and disconnects ground from the conductors extending to the contacts of the bank of wiper 352 of the sequence switch S at armatures 385-388, inclusive. As a further result of the placing of ground upon start conductor 247, the first four contacts in the bank of wiper 354 of the sequence switch S are grounded, whereupon a ground potential is extended from wiper 354 to wiper 351, by way of conductor 370, and thence by way of conductor 264 to the lower wiper 263 of the ofiice register OR. Since wiper 263 is in engagement with the. bank contact with which conductor 283 is connected, this ground potential extends by way of the associated IDF jumper to the seventh impulse conductor 297. From the seventh impulse conductor 297, this ground potential extends to conductor 367 by way of the resting contact of the upper armature of the seventh impulse counting relay 467 Fig. 7, and said armature. In response to the grounding of conductor 367, a circuit is closed for relay 380, Fig. 6, by way of the resting contact of armature 399 and said armature. Relay 380, upon energizin closes a circuit for itself independent 0% armature 399 and its resting contact at armature 412; connects up sending relay 381 at armature 411; and at armature 410 opens a point in the circuit of stepping magnet 350 and closes a circuit for slow acting relay 379. Relay 379 upon energizing, opens the initial circuit of relay 380 at armature 399, leaving relay 380 energized through contact; prepares a circuit I for stepping magnet 350 at armature 398; and at armature 397 places ground on locking conductor 368. Relay 381, upon energizing the first time ground is placed on conductor 371 by the rotary interrupter I after armature 411 is attracted, closes a circuit for the lower winding of pick-up relay 382 at armature 413; and at armature 414 removes ground from the outgoing im ulse conductor 248. This latter operation oes not have any effect, however, owing to the fact that con ductor 248 is at this time maintained grounded through armature 417 and its resting contact. P1ck-up relay 382, which is of the same marginal two-step type as relay 201, Fig. 4, energizes over its lower win just enough to operate the lightly adjuste armature 416, but not enough to operate the more stifliy adjusted armatures 415 and 417. When relay 381 deenergizes, it removes the shunt from around the upper winding of relay 382 at armature 413 and at armature 414 replaces ground on conductor 248. When this occurs, current flows through the two windings of relay 382 in series, whereupon the said relay energizes fully, thereby disconnecting armature 413 of sending relay 381 from its own windings and extending it by way of conductor 369 to armature 477 of the first impulse countin relay 461, Fig. 7. As afurther result of t e ener ation of relay 382, it disconnects ground rom conductor 248 at armature 417, leaving the said conductor grounded only through armature 414 and its resting contact. The next time relay 381 energizes, it removes ound from conductor 248 at armature 414, t ereby opening the circuit of repeating relay 127 of the repeater R, Fig. 3, and at armature 413 closes a circuit for the lower winding of the marginal two-step counting relay 461, whereupon relay 461 energizes part way and grounds its upper winding at armature 476. When relay 381 deenergizes again, it

opens the initial circuit of relay 461 at armature 413 and at armature 414 replaces the ground potential on conductor 248. When this occurs, relay 461 energizes fully; disconnects the first impulse conductor 291 from conductor 367 at armature 475; and at armature 477 extends conductor 369 to the corresponding armature of counting relay 462. As a result of the ground potential being replaced on conductor 248, the repeating relay of the repeater R energizes again. As sending relay 381 energizes and deenerarmature 412 and its working es, one of the impulse counting relays, F i g. 7, ulls part way up for each energ zation and all the way up or each deenergization thereof and, upon each energization of relay 381, ground is removed from the outgoing impulse conductor 248 at armature 414. This continues in the manner described until the seventh impulse counting relay 467 pulls all the way up as it does upon the eighth deenergization of sending relay 381, at which time ground will have been removed from the outgoing impulse conductor 248 seven times. elay 467, upon energizing fully, disconnects ground from conductor 367 at its upper armature, whereupon relay 380, Fig. 6, deenergizes; disconnects impulse relay 381 at armature 411 while the latter relay is still deenergized; and at armature 410 0 ns the circuit of slow acting relay 379 an closes a circuit for stepping magnet 350 of the sender S by way of armature 398 and its working contact. Relay 379 is slow acting and is adjusted so as to. hold up long enough to give the proper space between digits. Stepping magnet 350, of the sender upon energizing, merely advances the associated awl into engagement with the next notch in the ratchet wheel and does not move the w1 rs.

n the repeater R, Fig. 3, repeating relay 127, upon deenergizing in response to each of the seven interruptions produced in its circuit by sending relay 381 as described above, opens the circuit of line rela 163 of the selector D at armature 136. Fach time line relay 163 deenergizes, it closes the following circuit for vertical magnet 168: From ground by way of the resting contact of armature 182 and said armature, armature 174 and its resting contact, armature 176 and its working contact, series relay 165, and vertical magnet 168 to battery. By the operation of vertical ma et 168, the switch wipers 184-186, inclusive, are lifted step by step until they stand opposite the seventh level of bank contacts. Slow acting series relay 165 is maintained energized in series with vertical magnet 168 during the entire vertical movement. Upon the energization of series relay 165 and the closure of ofl normal contacts 173, which occur on the first vertical step, a circuit is closed from release trunk conductor 161 through armature 177 and its working contact, off normal contacts 173, and interrupter contacts 171, for stepping relay 166. Stepping relay 166, upon energizing, closes a locking circuit for itself at armature 178 and at armature 179 prepares a circuit for rotary magnet 172.

At the end of the vertical movement, relay 165 deenergizes and completes the circuit of rotary magnet 17 2 at armature 177. Rotary magnet 172, upon energizing, advances the wipers 184-186, inclusive, into engagement with the first set of bank contacts in the seventh level, and near'the end of its stroke, opens the circuit of stepping relay 166. Stepping relay 166, upon deenergizing, opens the circuit of rotary magnet 172 at armature 179, whereupon rotary magnet 172 deenergizes and closes its interrupter contacts again. In case the trunk terminating in the first set of bank contacts is idle, switching relay 167 energizes immediately. However, if the trunk is bus switching relay 167, being short circuite by the ground potential found on the test contact thereof by test wiper 185, does not energize. In this case, stepping magnet 166 energizes from ground on the busy test contact and again closes the circuit of rotary magnet 172 at armature 179, whereupon the switch wipers are advanced into engagement with the second set of bank contacts. This alternate operation of stepping magnet 166 and rotary magnet 172 continues until an idle trunk is reached, whereuponswitching rela 167, being no longer short circuited, energizes in series with stepping relay 166, the latter relay not energizing at this time on account of the high resistance of switching. relay 167. Switching relay 167, upon energizing, disconnects ground from armature 174 of line relay 163 at armature 182, thereby opening the circuit of release relay 164; o ens the test circuit and prepares the hol ing circuit at armature 181; and at armatures 180 and 183 disconnects conductors 160 and 162 from the windings of line relay 163 and extends them by wa of wipers 1'84 and 186 to the line relay 0 the trunk seized, whereupon the last named line relay and its associated release relay energize and the latter places ground on the release trunk conductor of the trunk, thereby establishing the usual holding circuit for switching relay 167 beforerelease relay 164 has had time to deenergize.

At the end of the predetermined interval, relay 379 deenergizes; prepares a circuit for relay 380 at armature 399; removes ground from conductor 368 at armature 397, whereupon pick-up relay 382 and such counting relays in Fig. 7 as are energized, deenergize; and at armature 398 opens the circuit of stepping magnet 350. Stepping mag et 350 now deenergizes and advances the wipers 351- 354, inclusive, of the sender S into engagement with the second set of bank contacts. Wiper 351, upon bein advanced, disconnects the grounded con uctor 370 from conductor 264 and connects it to conductor 265, thereby removing the ground from the lower or first digit wiper 263 of the office register OR and extending it to the second digit wiper 262. Since wiper 262 is in engagement with the bank contact with which conductor 282 is connected, and since conductor 282 is jumpered to the second impule conductor 292, ground is placed {on the ,latterg This ground potential extends by w g of conductor 292 andtherestin contact, of the upper armature ojthe; secon counting relay 462, Fig. 7 ,and said armature to. conductor 367. I In response; to the ground potential be. ing placed on conductor 367, re says-i380 and 379 energize one after-the other as in..- the r c d ea e n el y .8 be s to rate under the control Eof the interrupter I, each energizati'on afterzthefirst resulting in the removal of the ground potential from the outgoin in1pulse conductor-2418,.pic'kmp relay 382 bein operated .upon the .first eners gizationof -reiay 381, Since the controlling groundpotential. is coming in through the upper armature .of the second counting relay 462 at this time, ground is removed from: conductor 367 upon -the energization of the second counting rela 462, at-.whic h time the ground 130631112181. w1ll have been gremoved rom the outgoing impulseconductor 248 twice, thereby sending out the second 3, ofiice di 't 2, v Y

. he second de'.i'r,- peated by:relay 127 in the repeater R Fig- 3, the same as the first digit', andthe second selector to which .theconnection has been extended by-thefirst selectorD is operated in the usual manner to trunk the call tothe distant ofiice in whichthe called line .is located..

. When ground is removed from conductor 367, relays 380an d ,379. fa1l; back oneaft-er. the other in theorder.named,:thereby send:

' ing animpulse of currentlfto ste. ping mag net,35.0 of the sequence switch upon the deenergization of relay. 379,.which causes the wipers of the sequence switch-to ad vanced into, engagement with thethird set of bank contacts. Whenthis occurswiper; 351 disconnects the grounded. conductor 370 from conductor'265 and connects it. to con'- ductor 266, thereby 'rounding-the-third digit wiper 261 of the 0%ice register OR. .Since wiper 261 is inengagementwith conductor.

281, andsince conductor 281 is .jumpered to,

the third digit skip conductor 305, there-hes ing no -third digitin theofiice ,codejthis ground potential is extended toconductor 305. Whenconductor 305 is. grounded, step-v ping magnet 350 of the sequence. .switch; S- energizes through wiper 352, whioh is stand-Q ing on the bank contact. with which-conductor 305 is connected, and interrupts its, own circuit at contacts 349, whereuponit immediatel deenergizes and .advances; the; wipers of the sequence switch into fourth position. When this occurs, wiperv 351 disconnects the ground. potential from conductor, 266-. and

laces iton conductor 267 there by' groundmg the fourth digit: wiper260 of the ofiice register OR. Sincethe: ofiice to whichthe' call is going is an automatic ofiice, conductor 280 is jumperedkto, condu'ctor @302 v Conseq n ly,j h round Po t a extend byway of; conduotor 280, the associatedIDF jumper,

' conductor302, normally closed contacts con-,

353 reaches the ninth position instead-of; the;

tenth -position forwhich it is.-nor1na1liy set; n pl ce sr jmd c e qnwfi it-a mrture39l, thereby. causing the sequenceswitch S to. advancegautonia tic ally from. the iourth.

When the wipers of the sequenceswitch S; reach he-fift po n, per 354.. 9 160 17- ten t conduc or- Bfmvwh Qho wt nis grounded. only in; case thecallin subscriber e l e h fi s d g t et w dub"- scriberls number. Assuming, the first digit 5 in the subscribefls,nurnber-to.haveibeendialled prior to this time, as explained; hereinbefore, in; which case, conductor-..-357- is.

grounded, conductor .--370..-Qis; 1 grounded hr ugh. Wip 3 -.;0Qn q1.1e 1y, w 'p 351 heing in fifthsposition, places; ound on wiper 451 of the digit registerby. ye e uct 5. I inww per asn a v n e n we eg nt. wit the fifith associated bank contactin accord-; ance with j the, first. digit 5. in the desiredsubscribers number, 1 gas hereinbefore expla ned, w ve ti n d g n p en: tial [,is extended to; the ,fifth .4 impulse pooh-- fi reetende t dS mm nceatb omuc' r 6 1 3? w y 0? he .r ti lgae w o the uppe rm t ref. t fifths oun in l y 6. .;e ds d, ar t ":In' esp ns to the groundpotentialzbeing placed on con ductor 367 ,the; relay sender.- starts to. operatein. t e .PIQY I Sly de ibed. m nne andl since. the ground potential iszbeing g supplied o. q d ct r' 7. W y f: e h pulsev conductor295, five impulses are sent.

out atarmature 414..;at. this; time. Altillel Fig.

mm. t r e 01 'I P 1seS,..-g oun.d.i .e= I

m ed ro icn t r p0i1r ner: en o qun ng ir y ,-.W1. fel P0n; relays. 380 and 379.,fa1l. backone after the other e I us n i nn r, and the 'i'wipers" f 6 qu Sw h- Bi vanced into hflsix hpositi In the sixth i 'ositioir switch S, starting ground. is; siipplied to ip 5 yt ed g regis D byway.

of con u tor 3 .9, a s xte e bywiper 351 of the. sequence switch-to; iwiper 4 52 .ofthe digit .registerDR, byjwa coi conductor 338 Accordinglgythfi .secon digitifi in thej subscrihers nu er ,is sent out in; the-same n annerzas the first digit: 5, ,after which; the wipers oi, theseq enceyswitch are advanced into seventh;.,posltionl .1;

In the seventh position of the sequence switch S, ground 1s supplied to wiper 354 by the digit register DR by way of conductor 361, and in turn is supplied to wiper 453 of the digit register DR by wiper 351 of the sequence switch S by way of conductor 360. Consequently, the third digit 7 in the subscribers number is sent out in the usual manner, after which the wipers of the sequence switch are advanced 1nto the eighth position.

Similarly, in the eighth position of the sequence switch S, round is supplied to wiper 354 by the d1g1t register DR by way of conductor 363, and in turn is sup lied to the wiper 454 of the digit register R by wiper 351 of the sequence switch by way of conductor 362. Consequently, the fourth digit 8 in the subscribers number is sent out in the usual manner, at the end of which the wipers of the sequence switch are advanced into the ninth position in the previously described manner.

Responsive to the transmission of the four digits in the subscribers number, two selectors and a connector in the distant automatic ofiice are operated in the usual manner to complete the connection to the called subscribers line.

When the wipers of the sequence switch reach the ninth position, a circuit is closed for switch-through relay 376, Fig. 4, as follows: from ground by way of the working contact of armature 393 and said armature, ninth contact in the bank of se uence switch wiper 353 and said wiper, con uctor 243, armature 222 and its resting contact, normally closed contacts controlled by armature 389, and switch-through relay 376 to battery. Relay 376, upon energizing, locks itself to conductor 102 and opens its initial circuit at armature 389, and at armature 390 disconnects the incoming impulse conductor 101 from relay 202 and connects it to ground instead When this occurs, relay 126 in the repeater R energizes over the following circuit: from ground by way of the working contact of armature 390 and said armature, conductor 101, wiper 148 of the secondary switch SS, working contact of armature 143 and said armature, armature 129 of line relay 125 and its working contact, and relay 126 tobattery. Relay 126, upon energizing, locks itself to release trunk conductor 161 at armature 133' connects release trunk conductor 122 of t e repeater R with release conductor 161 of the selector D at armature 132; and connects the line conductors 121 and 123 of the repeater R with line conductors 160 and 162 of the selector D at armatures 130 and 135. The adjustment of the contacts of rela 126 is such that armatures 131 and 134 brea away from their resting contacts just after 06 armatures 130 and 135 make contact, thereby disconnecting line relay 125. The last circuit change produced by relay 126 is that it disconnects the local bridge from across conductors 160 and 162 at normally closed contacts controlled by armatures 130 and 135, thereby leaving the established connection under the direct control of the calling substation. The resistance 152 is included in the local bridge for the purpose of preventing unduly loud clicks when the local bridge andthe subscribers loop are placed to ether and separated.

11 the director, as a further result of the sequence switch S advancing to ninth position, wiper 354 engages conductor 365 which is the conductor that is grounded when the series relay of the fifth digit register DR comes to rest after the operation of the said switch DR. In this case the digit register DR has not been operated, but conductor 365 is normally grounded through armature 394 of relay 378 and its restin contact, and the ground potential is exten ed through the ninth contact of wiper 354 and said wiper, conductor 370, wiper 351, and conductor 364 to wiper 455 of the digit register DR. Since wiper 455 of the digit register DR is not operated, the placing of round thereon has no effect at this time. owever, conductor 364 is normally connected to the first impulse conductor 291 by way of the resting contact of armature 396 of relay 378 and said armature. Consequently, this ground potential extends from conductor 291 to conductor 367 by way of the restin contact of armature 475 of the firstvcountlng relay 461, Fig. 7, and the relay sender starts to send out the digit 1. The 0 eration of the sender at this time has no e ect, however, for the reason that the switch-over occurs immediatelyu pon the sequence switch being advanced to ninth position, as. hereinbefore explained, and the control of the connection is removed from the outgfciing repeating relay 127 in the repeater efore the first impulse comes along.

In the repeater R, Fig. 3, line relay 125 deenergizes in response to being cut off by relay 132 at armatures 1'31 and 134, as pointed out above, and opens'the initial circuit of relay 126 at armature 129, leaving relay 126 energized through its locking circuit which is closed at armature 133. As a further result of the deenergization of line relay 125, it opens the circuit of the slow acting line relay 137 of the secondary switch SS at armature 128. Relay 137, u on deenergizing, opens the circuit of switc ing relay 138 at armature 140, whereupon switching relay 138 deenergizes and disconnects wipers 148-151, inclusive. By this opera-' tion the ground potential is removed from conductor 104 of the director trunk, whereupon relay 208, Fig. 4, deenergizes but does not perform any particular function at this time. As a further result of the removal of the ground potential from conductor 104, the ground potential is removed from starting conductor 247, whereupon relay 375, Fig.

6, deenergizes and grounds all the contacts in the bank of wiper 352 of the sequence switch S. When this occurs, the wipers of the sequence switch are automatically advanced through its remaining positions and into the first position by the buzzer like action of the stepping magnet 350. When ground is removed from conductor 102 of the director trunk, relays 376, 204, and 205, Fig. 4, deenergize, and relay 204 places ground on release conductor 242 at armature 216, whereupon the ofiice register OR and the switch MDC are released in the usual manner. Conductor 242, it will be noted, is extended across the top of Fig. 7 and a lead is taken from the said conductor to the lower ofi normal contacts of each of the digit registers DR-DR*, inclusive. Accordingly, the release magnets of such digit registers as are off normal energize and restore the digit registers to normal position, the release magnet 446 of the digit register DR, for example, is energized through ofl normal contacts 448, and the circuit of release magnet 446 is opened at off normal contacts 448 when wiper 451 reaches normal position. The director is now in condition to be seized and to handle the next call.

Regarding the established connection, it may be said that the connection is released upon the hanging up of the subscriber at substation A by the removal of the ground potential from the release trunk conductor by the switch to which connection has been extended. WVhen this occurs, the switching relay 167 of the selector D, relay 126 of the repeater R, and switching relay 110 of the line switch C deenergize. The deenergization of relays 110 and 126 restores conditions in the line switch C and the repeater R to normal, and the deenergization of switching relay 167 of the selector D results in a circuit being closed for release magnet 169, which circuit includes armatures 182, 174, and 176, and off normal contacts 170. The selector D is restored to normal position in the usual manner upon the energization of release ma net 167, the circuit of release magnet 167 eing opened at off normal contacts 170 by the switch shaft when the latter reaches normal position.

It will be assumed now that the subscriber at substation A desires to converse with a subscriber whose line terminates in the manual party line oflice 92, whose line number is 1234, and whose station number is 5. It will be assumed further that, when the subscriber removes his receiver, his individual line switch C selects the trunk leading to the repeater R, and that the secondary switch SS selects the director trunk comprising conductors 101-104, inclusive, and also that the subscriber has dialled the first digit 9 in the number of the desired ofiice with the hereinbefore described results.

In response to the calling of the second oflice digit 2, the wipers 260-263, inclusive, of the ofiice register OR are advanced into engagement with the .second set of bank contacts in the ninth level. By the operation of rotary magnet 251 of the master digitcontrol switch MDC, the wipers thereof are advanced another step, whereupon the operating circuit is extended to stepping magnet 445 of the digit register DR by wiper 253. At the same time, ground is placed on start conductor 247 by wiper 254, whereupon the relay sender begins to send out the oflice code.

The calling subscriber now operates his calling device in accordance with the digits 1-5, inclusive, whereupon the digit registers DRDR, inclusive, respond in the usual manner to register the digits called, the necessary control being exercised by the master digit controller MDC as hereinbefore explained.

When the ground potential is placed on the start conductor 247 as pointed out above, ground is extended through the first contact in the bank of wiper 354 of the sequence switch S to conductor 370, and thence by way of wiper 351 of the sequence switch S, and conductor 264 'to the first digit wiper 263 of theoflice register OR. From an inspection of the drawings, it will become apparent that the first three-contacts from the bottom of the set with which the wipers of the ofiice register are now in engagement, or the contacts in which the conductors 277-. 279, inclusive, are terminated, are jumpered so as to send out the oflice code 850. Consequently, the ground potential on wiper 263 is extended over conductor 279 and the associated IDF jumper, to the eighth impulse conductor 298. That being the case, the relay sender operates in the previously described manner to send out the first digit 8 in the oflice code, after which an impulse of current is delivered to ste ping magnet 350 of switch S, whereupon t e wipers are advanced into second position and ground is placed on the second digit wiper 262 of the office register OR. This ground potential extends by way of bank conductor 278 and the associated IDF jumper to the fifth impulse conductor 295. Consequently, the second digit 5 in the ofiice code is sent out by the relay sender, after which the sequence switch S isadvanced into third position and the ground potential is extended over the third digit wiper 261, the bank contact with which it is in engagement, conductor 277, and the associated IDF jumper to the tenth impulse conductor 300, where- 'upon the third digit 0 in the office code is sent out. n 7

Responsive to the transmission of the i 5 three ofiice digits, the call is trunked through the automatic network to the desired-mans ual oifice, where call indicating apparatus is prepared for the reception of the digits in the called subscribers number.

'Whenthe wipers of the switch S are advanced into-fourth position after the sending out of the third digit in, the ofiice code, ground is placed on the fourth wiper of the oflice register OR, and is extended from thence by way of the bank contact with which it is in engagement, conductor 276, the associated IDF jumper,ring digit conductor 303, the normally closed contacts controlled by a-rmature 3950f relay 37 8, and relay 378 to battery. Relay 378, upon energizing, closes a locking circuit for itself and opens its initial circuit at armature 395; disconnects ground from conductor 365 at armature 394 so as to cause thesender to wait for the operation of the fifth digit register DR; disconnects the first impulse conductor 291 from conductor 364 at armature. 396, so as to leave the sender free to send out the digit set up on the digit register DR"; and at armature 394 placesgroundon conductor 306, thereby causing the switch S to advance, automatically from its fourth to its fifth position. I p

The sender now sends out the digits set up on the digit registers DR-DR, inclusive, in the hereinbefore. described manner, the sequence switchS being advanced automatically in the usual manner at the end of each digit. It will be noted that since relay 377 is not energized-at this time, ground is not placed on conductor 243 of wiper 35.3 of the sequence switch S until the sequence switch is advanced into its tenth position. Consequently, the director does not switch through until. the fifth or party selecting digit has been sent out and the sequence switch has been advanced totenth position. v

The five digits in the called number are registered by the call indicator in use at the manual office and at the proper time are displayed to an operator, who completes the connection inthe usual manner. 7

'Whenthe sequence switch reaches tenth position, conductor 243 is grounded, whereupon the director switches through in the hereinbefore described manner.

It will be assumed now that the subscriber at substation A desires to converse with a subscriber in the individual line manual office 93, whosev number is 1234. It will be assumed further that when the subscriber removes his receiver, the individual line switch C selects the trunk extending to the repeater'B," and'that the secondary switch SS, selects the director trunk comprising conductors 101-104, inclusive. That being the case, the ofiice register OR israised to the ninth level in response to the-dialling of the first office digit 9, and is rotated three steps in response to the dialling of the second digit 3, and the digit registers DR-DR, inclusive, are operated in response to the next four digits dialled and register such digits. I

The sender starts to send out the office code at the end of the dialling of the second ofiicedigit in the usual manner. It is assumed that the oflice code desired in the present. case is ,859. Accordingly, the conductors 275, 274, and 273. ofthe ninetythird set ofbank contacts of the ofiice register OR are jumpered to the eighth, fifth, and ninth impulse conductors, respectively. Since the ofiice to which the call is going is an individual line manual ofiice, no special relay needbe pulled up, and the fourth conductor 272 of the set isjjumperedto the fourth digit skip conductor 306. When the fourth digit wiper 260 of theoflice register OR is grounded bythe sequence switch S after the'sending out'of thethird digit 9 in theoflice code, ground-is extended by way of conductor. 272 and the associated I'DF jumpered to the fourth digit skip conductor 306, whereupon the wipers of the sender are advanced automatically into the fifth position. i

The sender now sends out the digit 1 4, inclusive, of the subscribers number in the usual manner, the sequence switch .S being advanced one step after each digit.

When the sequenceswitch S reaches-the ninth position, ground is supplied to conductor 370 by way of armature 394 of relay 378 and its resting contact, ninth contact in the bank of wiper 354, and wiper 354. This ground potential is extended by wiper 351 to conductor 364 and extends from thence tovthe first impulse conductor 291 by way of the resting contact ofarmature 396 and said armature. Consequently, the relay senderproceeds to sendout the digit 1, this digit being added automatically by the director in order, to switch the call indicator at the manual ofiice into displaying .position for reasons hereinbefore given. As soon as the digit .1 has been sent out, the sequence switch S is advanced into tenth position, whereupon ground is placed upon conductor 243'byway.of wiper 353, and the director switches through as a result.

In order to explain the operation of the director in calling the; long distance operator, it will be assumed that the subscriber at substation A desires to call the ion dis.- tance operator. It will be assume 'fur ther, that the connection is extended upon the removal of the receiver at-substation A to the director trunk which comprises conductors 101-104, inclusive, secondary switch SS. 7

When the calling subscriber operates his calling device in accordance with the digit 0, which digit is the one assigned to the long distance operator, the office register OR, Fig. 5,raises its wipers opposite the tenth level of bank contacts, which is the level in which the upper set of contacts shown in Fig. 5 is located; It will be remembered that relays 202. and 203, Fig. 4, are ener gized during the vertical movement of ofce register OR. Also, when the tenth level is reached, the switch shaft operates the tenth level springs 233-235, inclusive. Spring 233, upon being operated, disconnects the rotary magnet operating lead 246, so as to remove the rotary movement of the switch from under the control of the calling subscriber. Spring 235, upon coming into engagement with its associated contact, places ground upon the second contact in the bank of a wiper 254 of the master digit control switch MDC, so as. to cause wiper 254 to ground start conductor 247- when the master digit control switch is advanced to second position instead of the third as in other cases. The tenth level spring 234, upon being operated, prepares a circuit for rotary magnet 230. Relay 202, upon falling by way of the back at the end of the vertical movement,

opens the circuit of slow acting relay 203 at armature 212, at the same time closing the usual circuit for stepping magnet 251 of the switch MDC. A branch of this circuit extends by way of the working contact of armature 213 and the said armature, conductor 238, spring 234 and its upper contact, and rotary magnet 230 to battery. Stepping magnet 250 of the master digit control switch MDC, upon energizing, advances wipers 253 and 254 into engagement with the second set ofbank contacts and rotary magnet 230 of the otfice register OR, upon energizing, advances wipers 260-263, inclusive, into engagement with the first set of bank contacts in the tenth level, which is the set of contacts in which conductors 268- 271, inclusive, terminate. After an interval slow acting relay 203 falls back and opens the circuits of magnets 230 and 251 at armatures 213 and 214, respectively.

When wiper 254 is moved into engagement with its second bank contact, as described above, it places ground on start conductor 247, conductor 239 having" been grounded by tenth level spring 235. Con-j sequently, the relay sender starts to send out the code necessary to trunk the 'call to the long distance operator. 'The code in this case is assumed to be 46. Accordingly, conductor 271, Fig. 5, is jumpered to the fourth impulse conductor 294 and conductor 270 is jumped to the sixth impulse conductor 296.

In order to cause the director to switch through after the calling of the second digit 6 in the code conductor 269 is. jumpered to the code-number switch conductor 301. That being the case, when the third digit wiper 261 of the ofiice register OR is grounded by wiper 351 of the sequence switch S, Fig. 6, after the second digit 6 is sent out, the ground potential extends by way of conductor 269, the associated IDF jumper, codenumber switch conductor 301, and the third contact in the bank of sequence switch wiper 353, to switchconductor 243. Consequently, the director switches through in the hereinbefore described manner.

The operation of the improved director when used by a'paystation subscriber will now be considered; For this urpose, it will be assumed that the subscri r at substation A desires'to station A, as before explained, is of the paystation type and the subscriber thereat isinstructed to deposit a coin before dia When the receiver is removed, a brid is placed across line conductors 5 and 6, wfizreupon line relay8 of the line switchC energizes and closes the usual circuits at armatures 18 and 14, whereupon the line switch C selects an idle trunk, which trunk, it will be assumed, is the one comprising the conductors 18-20, inclusive. Switching relay 7 energizes when an idle trunk is reached or immediately upon the energization of line relay 8 in case the wipers 15-17, inclusive, are stand ing on an idle trunk when the call is initiated, and at armatures 10-12, inclusive,

switches the connection through to the Differential relay 32, however, does not energize until the circuit has been unbalanced by the depositing of a, coin at the substation. Line relay 35, upon energizing, closes a circuit for release relay 34 at armature 60. Release relay 34, upon energizing, piepares a circuit for relay 33 at armature 57, and at armature 58 places ground on eonductor 78, thereby grounding release trunk conductor 19 by way of the normally closed contacts controlled by armature 64, so alto establish the usual holding circuit for the line switchC. It will be noted that a cir-' cuit is closed for the lower winding of the electro polarized relay 31 from release trunk make a call. The subof I III 

